By-wire braking systems for a vehicle may include a backup braking system, typically a push-through device that mechanically delivers hydraulic fluid to brakes of a vehicle in the event of failure of a primary braking system that provides the hydraulic fluid to the brakes when the primary by-wire braking system is operational. It may be desirable to provide additional sources of braking energy for a backup braking system in the event of failure of the primary braking system. Furthermore, it may be desirable to provide additional sources of braking energy for a backup braking system without substantially increasing the complexity or cost of manufacture of a braking system.